
/* @(#)w_log10.c 5.1 93/09/24 */
/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

/*
FUNCTION
    <<log10>>, <<log10f>>---base 10 logarithms

INDEX
log10
INDEX
log10f

ANSI_SYNOPSIS
    #include <math.h>
    double log10(double <[x]>);
    float log10f(float <[x]>);

TRAD_SYNOPSIS
    #include <math.h>
    double log10(<[x]>)
    double <[x]>;

    float log10f(<[x]>)
    float <[x]>;

DESCRIPTION
<<log10>> returns the base 10 logarithm of <[x]>.
It is implemented as <<log(<[x]>) / log(10)>>.

<<log10f>> is identical, save that it takes and returns <<float>> values.

RETURNS
<<log10>> and <<log10f>> return the calculated value.

See the description of <<log>> for information on errors.

PORTABILITY
<<log10>> is ANSI C.  <<log10f>> is an extension.

 */

/*
 * wrapper log10(X)
 */

#include "fdlibm.h"
#include <errno.h>

#ifndef _DOUBLE_IS_32BITS

#ifdef __STDC__
    double log10(double x)      /* wrapper log10 */
#else
    double log10(x)         /* wrapper log10 */
    double x;
#endif
{
#ifdef _IEEE_LIBM
    return __ieee754_log10(x);
#else
    double z;
    struct exception exc;
    z = __ieee754_log10(x);
    if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;
    if(x<=0.0) {
#ifndef HUGE_VAL
#define HUGE_VAL inf
        double inf = 0.0;

        SET_HIGH_WORD(inf,0x7ff00000);  /* set inf to infinite */
#endif
        exc.name = "log10";
        exc.err = 0;
        exc.arg1 = x;
        exc.arg2 = x;
        if (_LIB_VERSION == _SVID_)
               exc.retval = -HUGE;
        else
           exc.retval = -HUGE_VAL;
        if(x==0.0) {
            /* log10(0) */
            exc.type = SING;
            if (_LIB_VERSION == _POSIX_)
               Djy_SaveLastError(ERANGE);
            else if (!matherr(&exc)) {
               Djy_SaveLastError(ERANGE);
            }
        } else {
            /* log10(x<0) */
            exc.type = DOMAIN;
            if (_LIB_VERSION == _POSIX_)
               Djy_SaveLastError(EDOM);
            else if (!matherr(&exc)) {
               Djy_SaveLastError(EDOM);
            }
                exc.retval = nan("");
            }
        if (exc.err != 0)
               Djy_SaveLastError(exc.err);
            return exc.retval;
    } else
        return z;
#endif
}

#endif /* defined(_DOUBLE_IS_32BITS) */
